The City of Boulder has started construction on a major trail improvement project at Mount Sanitas, one of the most popular hiking destinations in the region.
The multi-year project, led by Boulder’s Open Space and Mountain Parks (OSMP) department, aims to make the trails safer and more sustainable while protecting nearby wildlife habitat. Work began earlier this month and is expected to continue in phases through 2027.
The area sees close to 375,000 visitors each year, and years of heavy use have taken a toll on the landscape. Trails have widened, plants have been trampled, and erosion has worsened. This summer’s efforts will focus on repairing the steep summit approaches on both the Mount Sanitas and East Ridge trails. Crews will install new stone steps and reinforce existing trail tread to help reduce runoff and long-term maintenance needs.
In addition to trail repairs, OSMP is working with the Boulder Climbing Community to improve access to eight bouldering areas along the mountain. The work includes building safer access paths, designating areas for crash pad use, and restoring vegetation in areas that have been damaged by overuse.
The city also plans to close and restore several informal “social trails,” or unofficial paths created by repeated foot traffic. These closures will help protect sensitive plant life and wildlife habitat. New signage and short trail connections will help guide visitors onto designated routes. Two new trail connectors are also planned. One will link the existing trail system to nearby neighborhoods. The other will provide access to a historic quarry site.
Despite the construction, trailheads at Mount Sanitas, East Ridge and Lion’s Lair will remain open. OSMP says no full closures are expected, though hikers may encounter brief delays or detours while crews are on site.
The work is funded by a $1.1 million federal Land and Water Conservation Fund grant administered by Colorado Parks and Wildlife and the National Park Service. The Boulder Open Space Conservancy (BOSC), a nonprofit that supports OSMP, helped secure the funding.
“Mount Sanitas is an iconic Boulder open space area that has created special outdoor experiences for generations of community members and visitors from near and far,” said Alyson Duffey, executive director of BOSC. “We value our strong partnership with Open Space and Mountain Parks, and we look forward to continuing our shared work to ensure future generations can enjoy and protect Mount Sanitas.”
The Mount Sanitas upgrades are part of a larger slate of trail and habitat improvements OSMP is managing this year through its “Enjoy and Protect” initiative, which includes more than 300 projects across the city.
For trail updates and construction notices, visit osmptrails.org.
Information in this story was drawn from a City of Boulder press release published June 10, 2025.
